REPORT ON THE GASTEROPODA. 325 



a narrow rounded twisted edge. H. 0'61 in. B. 0"3. Penultimate whorl, height 0*1. 

 Mouth, height 0'31, breadth 0"19. 



This is a peculiar form, stamped essentially with the characteristics of a frigid-water species. 



55. Pleurotoma (Spirotropis) bulbacea, Watson (PI. XXV. fig. 9). 



Pleurotoma (Drillid) bulbacea, Watson, Prelim. Report, pt. 9, Journ. Linn. Soc. Lond., voL xv. 



p. 418. 



Station 169. July 10, 1874. Lat. 37° 34' S., long. 179° 22' E. North-east from 

 New Zealand. 700 fathoms. Blue mud. Bottom temperature 40°. 



Shell. — Broadish, conical, sharply keeled, strong, porcellanous, with a shortish con- 

 tracted base, a short snout, short narrow ribs, spiral threads, and a bulbous apex. 

 Sculpture : Longitudinals — below the sinus-area and about one-third down the whorl 

 from the suture arise, not quite abruptly, ribs slightly tubercled at the top, straight, 

 direct, narrow, and parted by shallow furrows about twice their breadth ; they become 

 feeble toward the lower suture ; on the last whorl they do not continue to the base, and 

 become broader and weaker toward the mouth : there are eleven on the last and penulti- 

 mate whorls ; on the first infra- embryonic whorl there are about seventeen, crowded, 

 sharp, scarcely curved and oblique. The lines of growth are numerous and unequal ; ' in 

 the sinus-area they are sharp and delicate, on the rest of the shell coarse and puckered. 

 Spirals — marginating the suture at the top of each whorl is a narrow scarcely swollen 

 band ; below this the sinus-area is very finely, almost microscopically, scratched ; and 

 this scratch-sculpture is continued, though less distinctly, on the rest of the surface. 

 The projection of the top of the ribs forms a sharp keel. The rib-area is crossed by five 

 coarsish threads, which rise into small tubercles on the ribs ; one or two smaller threads 

 come in between the lines of these spirals. The same sort of threads, but less distinct, 

 are found on the base ; those on the pillar and snout are a little more distinct. Colour 

 dull porcellanous white. Epidermis quite gone. Spire rather short, conical, very slightly 

 scalar, cylindrical toward the top. Apex two smooth embryonic whorls, swollen and 

 roundedly pressed down, with a deepish suture, rather more prominent than the regular 

 whorl which follows. Whorls 6^, short, of rather rapid increase ; the last large relatively 

 to the rest ; from the suture to the ribbing they are concavely shouldered. The projec- 

 tion of the tubercles at the top of the ribs forms a carination, which does not really exist 

 in the form of the whorls themselves ; there is a very slight contraction towards the 

 lower suture. The last whorl contracts slightly from the keel to the edge of the base, and 

 from that point rapidly to the small, narrow, straight, and direct snout. Suture coarse, 

 slightly impressed, and well defined by the band below it. Mouth narrowly oval, pointed 

 above, with an oblique, short, rather open and gradually contracted canal in front. Outer 



